JP2011004802A - Method for sterilization processing and sterilizer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently and efficiently sterilizing an object to be treated.SOLUTION: The sterilizer 100 uses nitrogen dioxide (NO) as a sterilizing agent; and includes a sterilization chamber 102 providing a sealed space for sterilization processing, a plasma generating part 103 for generating NOgas, a catalyst part 104, a purifying device 105 and a control part 109. NOgas is introduced into the sterilization chamber 102, and the object T to be treated is sterilized by exposing the object to the sterilizing agent. The sterilization processing satisfies the expression: T×D≥1,000 (kppm×min) while T≤120 min, when the time of exposure of the object T to NOgas is T (min) and the concentration of NOgas within the sterilization chamber 102 is D (kppm).

Description

  The present invention relates to a sterilization method and a sterilization apparatus for sterilizing an object to be processed using nitrogen oxide gas as a sterilant.

  As a method of highly sterilizing objects to be processed such as medical instruments and food packaging materials, nitrogen oxide gas as a sterilizing agent is introduced into the sealed space where the object to be processed is placed, and the sterilizing agent reacts with the object to be processed The method of making it known is known. For example, in Patent Document 1, a mixed gas of nitrogen gas and oxygen gas is introduced into a plasma generation chamber, the mixed gas is converted into plasma to generate nitrogen oxide gas, and this nitrogen oxide gas is attached to food. The technique used for sterilization of the is disclosed.

JP 58-162276 A

  However, in the case of using nitrogen oxide gas as a sterilant, it has not yet been fully clarified whether under what conditions sterilization can be performed to sterilize the workpiece reliably and industrially efficiently. Patent Document 1 discloses the use of nitrogen oxide gas, but does not disclose any specific conditions.

  The present invention has been made in view of the above points, and provides a sterilization method and a sterilization apparatus that can efficiently sterilize an object to be processed while efficiently performing sterilization. For the purpose.

A sterilization method according to one aspect of the present invention that achieves the above object is a method of performing a sterilization process in which an object to be processed is exposed to a sterilant in a sealed space, and using nitrogen oxide gas as the sterilant, As the sterilization treatment, when the exposure time of the object to be treated with the nitrogen oxide gas is T (min) and the concentration of the nitrogen oxide gas in the sealed space is D (kppm), the sterilization treatment satisfying the following formula: (Claim 1).
T × D ≧ 1000 (kppm · min) where T ≦ 120 min

  According to this method, the sterilization process that satisfies the minimum exposure condition determined by the exposure time T and the nitrogen oxide gas concentration D is performed, so that sufficient sterilization of the workpiece is ensured. Moreover, since the upper limit of the exposure time T is determined, an efficient sterilization process can be performed.

  In the above method, the sterilization treatment includes a first step of sealing a space for accommodating the workpiece to form a sealed space, and gradually increasing the concentration of nitrogen oxide gas in the sealed space; A second step of holding for a predetermined time after reaching the concentration, and the concentration D of the nitrogen oxide gas may be an equivalent concentration combining the first step and the second step. (Claim 2).

  According to this configuration, the sterilization of the object to be processed is performed while the nitrogen oxide gas is generated in the sealed space or the nitrogen oxide gas stored in another space is gradually exchanged with the gas in the sealed space. Processing can be performed.

  In this case, it is desirable that the nitrogen oxide gas is a gas containing nitrogen dioxide as a main component. According to this configuration, the sterilization efficiency can be further improved.

A sterilization apparatus according to another aspect of the present invention includes a first chamber in which an object to be processed is accommodated, a second chamber in which nitrogen oxide gas as a sterilizing agent is generated, and the first chamber to the first chamber. A first pipe that forms a communication path toward the first chamber, a second pipe that forms a communication path from the first chamber to the second chamber, a first valve disposed in each of the first pipe and the second pipe, and A circulation means for circulating gas in a sealed space formed by a second valve, the first pipe and the second pipe, the first chamber, and the second chamber; the first valve; Control means for controlling the operation of the two valves and the circulation means, wherein the control means opens the first valve and the second valve, drives the circulation means, and drives the circulation means in the sealed space. Circulating a gas containing nitrogen oxide gas, Sterilization treatment for exposing an object to a gas containing the nitrogen oxide gas, the exposure time of the object to be treated with the nitrogen oxide gas being T (min), and nitrogen in the sealed space When the concentration of the oxide gas is D (kppm), the circulation is maintained so that a sterilization process that satisfies the following formula is performed (claim 4).
T × D ≧ 1000 (kppm · min) where T ≦ 120 min

 According to this configuration, the sterilization process that satisfies the minimum exposure condition determined by the exposure time T and the nitrogen oxide gas concentration D is performed, so that sufficient sterilization of the object to be processed is ensured and the upper limit of the exposure time T is set. Therefore, it is possible to provide a sterilization apparatus capable of performing an efficient sterilization process.

  ADVANTAGE OF THE INVENTION According to this invention, while performing sufficient sterilization processing with respect to a to-be-processed object, the sterilization processing method and sterilization apparatus which can perform the efficiency of sterilization processing efficiently can be provided.

It is a block diagram which shows the sterilizer which concerns on 1st Embodiment of this invention. It is a graph which shows the sterilization effect by the sterilizer of 1st Embodiment. It is a block diagram which shows the sterilizer which concerns on 2nd Embodiment of this invention. It is a block diagram which shows the structure of a microwave supply apparatus roughly. It is sectional drawing which shows the plasma nozzle of the state attached to the waveguide. It is a block diagram showing a detailed configuration of the NO ₂ conversion unit. It is a block diagram which shows the electrical control system of a sterilizer. It is a timing chart which shows operation | movement of a sterilizer. It is a table format figure which shows the control state of a pump. It is a table format figure which shows the control state of a solenoid valve.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First Embodiment]
FIG. 1 is a block diagram showing a sterilization apparatus 100 according to the first embodiment of the present invention. The sterilization apparatus 100 is a sterilization apparatus using nitrogen dioxide (NO ₂ ) as a sterilant, and includes an introduction unit 101, a sterilization chamber 102 (sealed space), a plasma generation unit 103, a catalyst unit 104, a purification device 105, and a control unit 109. including. The sterilization chamber 102 is provided with an intake system introduction pipe 106, a circulation pipe 107, and an exhaust system exhaust pipe 108.

  The introduction unit 101 includes a first pump P11 and a first electromagnetic valve V11 provided in the introduction pipe 106, and introduces air from the outside into the sterilization chamber 102 via the introduction pipe 106. Note that the gas may be introduced into the sterilization chamber 102 from a cylinder in which a gas containing nitrogen and oxygen is sealed.

The sterilization chamber 102 is a sealed chamber capable of storing NO ₂ gas. The sterilization chamber 102 includes a tray on which the object to be processed T is placed, and the object to be processed can be sterilized in the sterilization chamber 102.

  One end and the other end of the circulation pipe 107 are connected to the sterilization chamber 102. The circulation pipe 107 includes a second electromagnetic valve V12, a plasma generation unit 103, a second pump P12, a catalyst unit 104, and a third electromagnetic valve V13 in order from the upstream side in the fluid circulation direction (indicated by an arrow in the drawing). Is arranged.

The plasma generation unit 103 converts the sterilization raw material (air) into plasma, and generates nitrogen oxide gas (NO _x ) as a sterilization source. As this plasma generation unit 103, an atmospheric pressure plasma generation device including a microwave supply device and a plasma nozzle that is supplied with microwave energy from the microwave supply device and converts the raw material gas into plasma can be applied.

The catalyst unit 104 is a catalyst that converts a sterilization source into a sterilized substance, and converts NO _x generated by the plasma generation unit 103 into NO ₂ .

In the exhaust pipe 108, a purification device 105, a fourth electromagnetic valve V14, and a third pump P13 are arranged. The purifying device 105 is a NO ₂ removal catalyst, detoxifies the NO ₂ remaining in the sterilization chamber 102 after sterilization, and exhausts it.

The control unit 109 controls the operation of the plasma generation unit 103 and also controls the opening and closing operations of the first to fourth electromagnetic valves V11 to V14 and the operations of the first to third pumps P11 to P13, and the sterilization chamber. A sterilization process is performed in 102 to expose the object to be processed T to NO ₂ as a sterilant. This sterilization process is a sterilization process that satisfies the following equation, where T (min) is the exposure time of the object T to be treated with NO ₂ gas and D (kppm) is the concentration of NO ₂ gas in the sterilization chamber 102.
T × D ≧ 1000 (kppm · min) where T ≦ 120 min

According to such a sterilization process, the sterilization process that satisfies the minimum exposure condition determined by the exposure time T and the NO ₂ gas concentration D is performed, so that sufficient sterilization of the workpiece T is ensured. Moreover, since the upper limit of the exposure time T is determined, an efficient sterilization process can be performed. In a sterilization treatment that does not satisfy the minimum exposure condition of less than 1000 (kppm · min), there are cases where sufficient sterilization of bacteria cannot be achieved. The condition of T ≦ 120 min is set from the viewpoint that an excessively long exposure time T is not industrially appropriate.

  The operation of the sterilizer 100 configured as described above will be described. The control unit 109 opens the fourth electromagnetic valve V14 of the exhaust system, operates the third pump P13, and depressurizes the inside of the sterilization chamber 102. Thereafter, the first electromagnetic valve V11 of the introduction unit 101 is opened, the second to fourth electromagnetic valves V12 to V14 are closed, and the first pump P11 is operated to introduce air into the sterilization chamber 102.

Subsequently, the control unit 109 opens the second and third electromagnetic valves V12 and V13, closes the first and fourth electromagnetic valves V11 and V14, operates the second pump P12, and sterilizes the chamber 102 and the circulation pipe 107. Circulate air between them. When air passes through the circulation pipe 107, it is converted into plasma by the plasma generation unit 103 to generate NO _{x, and} is converted to NO ₂ by the catalyst unit 104. Thereby, the NO ₂ gas concentration in the sterilization chamber 102 gradually increases (first step). At the same time, sterilization of the workpiece T is also started.

By continuing the circulation of air through the circulation pipe 107 for a predetermined period, the sterilization chamber 102 stores NO ₂ gas having a desired concentration. When the concentration sensor (not shown) detects that the NO ₂ gas concentration in the sterilization chamber 102 has reached a predetermined concentration, the control unit 109 closes all the first to fourth electromagnetic valves V11 to V14, This state is maintained for a predetermined time (second step). During this period, the workpiece T is exposed to NO ₂ gas. The NO ₂ gas reacts with the workpiece T and the workpiece T is sterilized.

In the embodiment in which sterilization is performed while generating NO ₂ gas as in this embodiment, the exposure time T in the above conditional expression is the total time of the first step and the second step. The NO ₂ gas concentration D is calculated as an equivalent exposure concentration that combines the gas concentration in the sterilization chamber 102 in the first step and the gas concentration in the second step. For example, it is assumed that NO ₂ gas having a concentration of 24 kppm is generated by spending 60 min in the first step and is held for 60 min in the subsequent second step. In this case, since the average exposure concentration during the period of the first step is 12 kppm, the equivalent exposure concentration is calculated as 18 kppm by proportionally dividing the time ratio between the first step and the second step. The control unit 109 causes the total of the first step and the second step to execute a sterilization process that satisfies the condition of T × D ≧ 1000 (kppm · min) under the restriction of T ≦ 120 min.

After the sterilization process is finished, the control unit 109 opens the fourth electromagnetic valve V14, closes the first to third electromagnetic valves V12 to V14, and operates the third pump P13. As a result, the NO ₂ gas remaining in the sterilization chamber 102 is rendered harmless by the purification device 105 and then exhausted.

<Example>
Using a cylindrical chamber (sterilization chamber 102) with a volume of 40 liters, the pressure in the chamber was 1 atm, and the temperature was 25 ° C., respectively, under the conditions of Examples 1 to 5 and Comparative Examples 1 to 7 shown in Table 1 below. Sterilization was performed. In Table 1, “NO ₂ generation time” corresponds to the time of the first step, and “holding time” corresponds to the time of the second step. Further, “NO ₂ reached concentration” indicates the concentration at the timing of shifting to the second step. The exposure time T and the equivalent exposure concentration D are as described above. As the object to be processed, two “Cycle Sure BI” (registered trademark) manufactured by Johnson & Johnson, which is a biological indicator, were used and arranged in the center of the bottom of the chamber.

  As shown in Table 1, it was confirmed that in the sterilization treatments of Examples 1 to 5 that satisfy the condition of T × D ≧ 1000 (kppm · min), sterilization with respect to “Cycle Sure BI” is surely performed. FIG. 2 is a graph in which the results of Table 1 are plotted. In the figure, ◯ indicates Examples 1 to 5, Δ indicates Comparative Examples 1 to 4, and X indicates Comparative Examples 5 to 7, respectively. The curve of “sterilization limit” shown in FIG. 2 corresponds to T × D = 1000 (kppm · min). From the results of Examples 1 to 5 and Comparative Examples 1 to 7, It is understood that the “sterility limit” curve is significant.

[Second Embodiment]
FIG. 3 is a block diagram showing a sterilization apparatus 1 according to the second embodiment of the present invention. The sterilization apparatus 1 uses, for example, medical instruments such as a scalpel, forceps, and catheter, and food packaging materials such as packaging sheets, trays, and bottles to be processed, and applies a sterilizing agent to these to perform sterilization processing. Device. Also in this embodiment, NO ₂ gas is used as a sterilizing agent.

  The sterilizer 1 includes a main chamber 11 (first chamber), a sub chamber 12 (second chamber), an intake system 20, a circulation system 30, a linkage system 40, and an exhaust system 50. The first to eighth electromagnetic valves V1 to V8 and the first pump P1 to the fourth pump P4 are arranged at appropriate positions of these systems 20 to 50.

  The main chamber 11 is a chamber that provides a sealed space in which an object to be processed is accommodated. For example, the main chamber 11 is a large-capacity chamber that is made of stainless steel and has a pressure-resistant structure that can cope with a high degree of vacuuming. Although not shown, the main chamber 11 is provided with a door for loading and unloading a workpiece, and a processing tray for loading the workpiece is provided therein.

The main chamber 11 is provided with a first concentration sensor 111 that measures the concentration of the sterilant and a first pressure sensor 112 that detects the pressure in the chamber. The first concentration sensor 111 measures the concentration of NO ₂ as a sterilizing agent, and the measured value of the first concentration sensor 111 is referred to when the main chamber 11 is exhausted after the sterilization process. The first pressure sensor 112 is a sensor that measures the reduced pressure state in the main chamber 11. In addition, various physical quantity sensors such as a temperature sensor, a humidity sensor, or an ozone sensor may be provided.

The sub-chamber 12 is a chamber for generating a sterilizing agent, and is made of, for example, stainless steel. Like the main chamber 11, the sub-chamber 12 is a chamber with a relatively small capacity having a pressure-resistant structure capable of handling a high degree of evacuation. is there. As will be described in detail later, a predetermined concentration of NO ₂ gas is generated under normal pressure in the sub-chamber 12, and the NO ₂ gas is introduced into the main chamber 11 under reduced pressure.

Also in the sub-chamber 12, a second concentration sensor 121 that measures the concentration of NO ₂ and a second pressure sensor 122 that detects the pressure in the chamber are provided. The measured value of the second concentration sensor 121 is referred to, for example, to confirm whether or not NO ₂ gas having a predetermined concentration is generated in the sub-chamber 12 before introducing NO ₂ gas into the main chamber 11. .

  The intake system 20 is a piping system for introducing dried outside air (air) into the sub chamber 12 or both the sub chamber 12 and the main chamber 11. The intake system 20 includes a first pump P1, an air dryer 21, a humidity sensor 22, a first electromagnetic valve V1, a first atmospheric pressure pipe 201, and a first vacuum pipe 202. The first normal pressure pipe 201 is a pipe connecting the first pump P1 and the first electromagnetic valve V1, and the air dryer 21 and the humidity sensor 22 are arranged in the path. The first vacuum pipe 202 connects between the first electromagnetic valve V <b> 1 and the subchamber 12.

  The first pump P1 is a pump that is operated when the sub-chamber 12 in a reduced pressure state or both the sub-chamber 12 and the main chamber 11 are returned to normal pressure. The first pump P <b> 1 sucks outside air and sends the outside air into the sub chamber 12 through the first normal pressure pipe 201 and the first vacuum pipe 202. The air dryer 21 removes moisture contained in the outside air. For example, a drying device including an electric heater is applied. The air that has passed through the air dryer 21 has substantially zero humidity. The humidity sensor 22 detects the humidity of the air flowing through the first normal pressure pipe 201. The humidity sensor 22 is exclusively used for detecting a failure of the air dryer 21.

  The first electromagnetic valve V1 is a valve that is “opened” in conjunction with the operation of the first pump P1. That is, the first electromagnetic valve V1 is “closed” when the system including the main chamber 11 and the sub-chamber 12 needs to be shut off from the external pressure, and “open” when the system is returned to normal pressure. Is done. For this reason, the first vacuum pipe 202 having resistance to evacuation is used downstream of the first electromagnetic valve V1 in the intake direction.

The circulation system 30 is a system that is operated when the dry air introduced into the sub-chamber 12 by the intake system 20 is mainly ionized by plasma to generate NO ₂ gas as a sterilant. The circulation system 30 includes a second solenoid valve V2, a third solenoid valve V3, a flow rate control valve FV, a plasma nozzle 31, a gas flow meter 32, a second pump P2, a NO ₂ converter 33, a second vacuum pipe 301, a third A vacuum pipe 302 and a second atmospheric pressure pipe 303 are included.

One end side of the second vacuum pipe 301 communicates with the sub-chamber 12, and the other end side is connected to one end side of the second atmospheric pressure pipe 303 via the second electromagnetic valve V2. One end side of the third vacuum pipe 302 communicates with the sub-chamber 12, and the other end side is connected to the other end side of the second atmospheric pressure pipe 303 via the third electromagnetic valve V3. Thereby, a loop line that communicates with the sub-chamber 12 and returns to one end side of the third vacuum pipe 302 starting from one end side of the second vacuum pipe 301 is formed. In the present embodiment, the second vacuum pipe 301 side is the upstream side of the air flow flowing in the loop pipe line. A flow control valve FV, a plasma nozzle 31, a gas flow meter 32, a second pump P2, and a NO ₂ conversion unit 33 are arranged in order from the upstream side with respect to the second atmospheric pressure pipe 303.

The second solenoid valve V2 and the third solenoid valve V3 are “closed” when the sub-chamber 12 is in a reduced pressure state, and “open” during NO ₂ gas generation and detoxification processing in a normal pressure state to be described later. Is a valve. For this reason, the second vacuum pipe 301 and the third vacuum pipe 302 are applied as pipes connecting the second electromagnetic valve V2 and the third electromagnetic valve V3 and the sub-chamber 12.

  The flow control valve FV is a valve that is disposed in the second normal pressure pipe 303 on the upstream side of the plasma nozzle 31 and restricts the flow rate of the gas transferred through the second normal pressure pipe 303.

The plasma nozzle 31 provides an electric field concentration part for generating plasma (ionized gas). The air flowing through the second normal pressure pipe 303 is ionized by passing through the electric field concentration portion of the plasma nozzle 31 and converted into nitrogen oxide (NO _x ) gas containing NO ₂ gas or NO gas. In order to generate such plasma, microwave energy is used in this embodiment. The microwave energy is given to the plasma nozzle 31 from the microwave supply device 60.

  FIG. 4 is a block diagram schematically showing the configuration of the microwave supply device 60. The microwave supply device 60 is a device for generating microwave energy and supplying the microwave energy to the plasma nozzle 31, and a microwave generation device 61 for generating a microwave and a waveguide for propagating the microwave. A tube 62. The plasma nozzle 31 is attached to the waveguide 62. An isolator 63, a coupler 64, and a tuner 65 are provided between the microwave generator 61 and the waveguide 62.

  The microwave generator 61 includes, for example, a microwave generation source such as a magnetron that generates a microwave of 2.45 GHz, and an amplifier that adjusts the intensity of the microwave generated by the microwave generation source to a predetermined output intensity. including. In the present embodiment, for example, a continuously variable microwave generator 61 that can output microwave energy of 1 W to 3 kW is preferably used.

  The waveguide 62 is made of a nonmagnetic metal such as aluminum, has a long tubular shape with a rectangular cross section, and propagates the microwave generated by the microwave generator 61 in the longitudinal direction thereof. A sliding short 621 is attached to the far end side of the waveguide 62 via a flange portion 622. The sliding short 621 is a member for adjusting the standing wave pattern by changing the reflection position of the microwave.

  The isolator 63 is a device that suppresses the incident of the reflected microwave from the waveguide 62 to the microwave generator 61, and includes a circulator 631 and a dummy load 632. The circulator 631 directs the microwave generated by the microwave generator 61 toward the waveguide 62 while directing the reflected microwave toward the dummy load 632. The dummy load 632 absorbs the reflected microwave and converts it into heat. The coupler 64 measures the intensity of the microwave energy. The tuner 65 includes a stub that can project into the waveguide 62, and is an apparatus for performing adjustment that minimizes the reflected microwave, that is, adjustment that maximizes the consumption of microwave energy at the plasma nozzle 31. . The coupler 64 is used for this adjustment.

  FIG. 5 is a cross-sectional view showing the plasma nozzle 31 attached to the waveguide 62. The plasma nozzle 31 includes a center conductor 311, an outer conductor 312, a spacer 313, and a protective tube 314.

  The center conductor 311 is made of a rod-shaped member made of a highly conductive metal, and the upper end portion 311B side thereof protrudes into the waveguide 62 by a predetermined length. The protruding upper end portion 311B functions as an antenna portion that receives the microwave propagating in the waveguide 62.

  The outer conductor 312 is a cylindrical body made of a highly conductive metal and having a cylindrical space 312H (plasma generation space) that houses the central conductor 311. The central conductor 311 is disposed on the central axis of the cylindrical space 312H. The outer conductor 312 is fixed to the waveguide 62 by being fitted into a cylindrical metal flange plate 623 integrally attached to the lower surface plate of the waveguide 62 and tightened with a screw 624. As a result of the waveguide 62 being grounded, the outer conductor 312 is also grounded.

  The outer conductor 312 has a gas supply hole 312N that penetrates from the outer peripheral wall to the cylindrical space 312H. The upstream side of the second normal pressure pipe 303 is connected to the gas supply hole 312N. On the other hand, an insulating pipe 315 is connected to the lower end of the cylindrical space 312H. The pipe 315 constitutes a part of the second normal pressure pipe 303. Thereby, the gas which distribute | circulates the inside of the 2nd normal pressure piping 303 passes through the inside of the cylindrical space 312H.

  The spacer 313 holds the central conductor 311 and seals the space between the waveguide 62 and the cylindrical space 312H. As the spacer 313, for example, an insulating member made of a heat-resistant resin material such as polytetrafluoroethylene, ceramic, or the like can be used. A step portion is provided at the upper end portion of the cylindrical space 312H of the outer conductor 312 and the spacer 313 is supported by the step portion. The center conductor 311 held by the spacer 313 is insulated from the outer conductor 312. The protection tube 314 is made of a quartz glass pipe or the like having a predetermined length, and is fitted into the lower end portion of the cylindrical space 312H in order to prevent abnormal discharge (arcing) at the lower end edge 312T of the outer conductor 312.

According to the plasma nozzle 31 configured as described above, when the center conductor 311 receives the microwave propagating through the waveguide 62, a potential difference is generated between the outer conductor 312 and the ground potential. In particular, an electric field concentration portion is formed in the vicinity of the lower end 311T of the center conductor 311 and the lower end edge 312T of the outer conductor 312. In this state, when a gas (air) containing oxygen molecules and nitrogen molecules is supplied from the gas supply hole 312N to the cylindrical space 312H, the gas is excited to generate plasma (ionized gas) in the vicinity of the lower end portion 311T of the center conductor 311. ) Occurs. The plasma contains NO _x and free radicals. Although this plasma has an electron temperature of several tens of thousands of degrees, the gas temperature is a reactive plasma that is close to the outside temperature (a plasma in which the electron temperature indicated by electrons is extremely high compared to the gas temperature indicated by neutral molecules). It is a plasma generated under normal pressure.

  Here, the cylindrical space 312H for generating plasma is a space capable of generating plasma under atmospheric pressure as described above, but the second pump P2 is disposed immediately downstream of the cylindrical space 312H. Therefore, the inside of the cylindrical space 312H and the insulating pipe 315 is slightly negative pressure due to the generation of a gas flow accompanying the operation of the second pump P2. The fact that the flow control valve FV is provided immediately upstream of the cylindrical space 312H also contributes to the formation of a negative pressure in the gas transfer space between the flow control valve FV and the second pump P2.

  As described in the first embodiment, as a result of reducing the pressure of the cylindrical space 312H, stable lighting of plasma in the plasma nozzle 31 and maintenance of the lighting state are ensured. Incidentally, if the second pump P2 is arranged on the upstream side of the plasma nozzle 31, the cylindrical space 312H has a positive pressure slightly higher than the atmospheric pressure, which is an undesirable environment for lighting and maintaining the plasma.

Returning to FIG. 3, the gas flow meter 32 measures the flow rate of the gas flowing through the second atmospheric pressure pipe 303. The second pump P2 is a pump for circulating gas in one space formed by the sub-chamber 12 and the loop line of the circulation system 30 when generating NO ₂ gas. When the second pump P2 is operated while the plasma nozzle 31 is operating, the gas repeatedly passes through the cylindrical space 312H that generates plasma, and the concentration of NO ₂ gradually increases. As the second pump P2, a chemical-resistant pump having resistance to NO _x or the like is used.

The NO ₂ conversion unit 33 has a function of extracting NO ₂ from a gas that passes through the plasma nozzle 31 and contains various substances. FIG. 6 is a block diagram showing a detailed configuration of the NO ₂ conversion unit 33. The NO ₂ conversion unit 33 includes a filter 331 that adsorbs HNO ₃ from the gas delivered from the plasma nozzle 31, a first conversion unit 332 that converts NO _x in the gas that has passed through the filter 331 to NO, and then And a second conversion unit 333 that converts NO into NO ₂ .

When air is ionized in the plasma nozzle 31, NO and O ₃ are generated. These are oxidized stepwise by the reaction according to the following formula, and finally are partially removed into nitric acid (HNO ₃ ) by the reaction with moisture that remains slightly without being removed by the air dryer 21.
NO + O ₃ → NO ₂ + O ₂
2NO ₂ + O ₃ → N ₂ O ₅ + O ₂
N ₂ O ₅ + H ₂ O → 2HNO ₃

The filter 331 adsorbs HNO ₃ produced by the above reaction. As the filter 331, for example, a filter in which a nitric acid-adsorbing coating layer is applied to a base material having a ceramic honeycomb structure can be used. As the nitric acid-adsorbing coating layer, for example, a silicon adsorbent such as zeolite, alumina, or silica gel can be used.

The first converter 332 converts NO _x other than NO ₂ contained in the gas that has passed through the filter 331 into NO. As the first converter 332, for example, a catalyst provided with a catalyst in which a coating layer containing platinum, palladium or the like is formed on a substrate having a ceramic honeycomb structure, and a heater for adjusting the temperature of the catalyst An apparatus can be used.

Second converter 333 converts the NO contained in the gas passing through the first converter 332 into NO _2. Similarly, the second conversion unit 333 includes a catalyst in which a coating layer containing platinum, palladium, or the like is formed on a substrate having a ceramic honeycomb structure, and the temperature of the catalyst (of the first conversion unit 332). A catalyst device provided with a heater for adjusting the temperature (different from the catalyst) can be used.

  Next, the linkage system 40 is a system for communicating between the main chamber 11 and the sub chamber 12. The linkage system 40 includes a fourth solenoid valve V4 (first valve), a fifth solenoid valve V5 (second valve), a third pump P3 (circulation means), a fourth vacuum pipe 401 (first pipe), and a fifth vacuum. A pipe 402 (second pipe) is included.

One end (upstream end) of the fourth vacuum pipe 401 is connected to the sub chamber 12, and the other end (downstream end) is connected to the main chamber 11. A third pump P3 is disposed upstream of the fourth vacuum pipe 401, and a fourth electromagnetic valve V4 is disposed downstream. The third pump P3 is a chemical-resistant pump, and when the sub-chamber 12 is evacuated, when NO ₂ gas is introduced (circulated) from the sub-chamber 12 to the main chamber 11 for sterilization, It operates when the chamber 11 is evacuated and detoxified. The fourth solenoid valve V4 is a valve that is “opened” when the third pump P3 operates.

  One end side (upstream end) of the fifth vacuum pipe 402 is connected to the main chamber 11, and the other end side (downstream end) is connected to the sub-chamber 12. A downstream end of a seventh vacuum pipe 502, which will be described later, joins an intermediate portion of the fifth vacuum pipe 402. The fifth electromagnetic valve V <b> 5 is attached to the fifth vacuum pipe 402 at a position upstream from the joining portion of the seventh vacuum pipe 502. The fifth electromagnetic valve V5 is a valve that is “opened” when the main chamber 11 and the sub-chamber 12 are returned to normal pressure during sterilization.

The exhaust system 50 is a system for detoxifying the NO ₂ gas used for the sterilization process in the sealed space and exhausting the detoxified gas to the outside. The exhaust system 50 includes an HNO ₃ converter 51, a filter 52, a sixth electromagnetic valve V6, a seventh electromagnetic valve V7, an eighth electromagnetic valve V8, a fourth pump P4, a sixth vacuum pipe 501, a seventh vacuum pipe 502, 4 normal pressure piping 503 and 5 normal pressure piping 504 are included.

One end side (upstream end) of the sixth vacuum pipe 501 is connected to the main chamber 11, and the other end side (downstream end) is connected to one end side (upstream end) of the fourth atmospheric pressure pipe 503 via the sixth electromagnetic valve V6. It is connected. The other end side (downstream end) of the fourth atmospheric pressure pipe 503 communicates with the outside through the fourth pump P4. An HNO ₃ conversion unit 51, a filter 52, and an eighth electromagnetic valve V8 are attached to the fourth normal pressure pipe 503 in order from the upstream side. One end side (upstream end) of the fifth normal pressure pipe 504 is connected to the fourth normal pressure pipe 503 between the filter 52 and the eighth electromagnetic valve V8, and the other end side (downstream end) is connected to the seventh electromagnetic valve V7. Is connected to one end side (upstream end) of the seventh vacuum pipe 502. The other end side (downstream end) of the seventh vacuum pipe 502 is connected to an intermediate portion of the fifth vacuum pipe 402. If the first solenoid valve V1 and the eighth solenoid valve V8 are “closed” as a result of the provision of the fourth normal pressure pipe 503 and the seventh vacuum pipe 502, the main chamber 11, the exhaust system 50, the linkage The system 40 and the subchamber 12 can be made into one sealed space.

  The sixth electromagnetic valve V6 is a valve that is “opened” when the main chamber 11 and the sub chamber 12 are depressurized, detoxified, and then exhausted. The seventh solenoid valve V7 is a valve that is “opened” only during the detoxification process. The eighth electromagnetic valve V8 is a valve that is “opened” when the main chamber 11 and the sub chamber 12 are depressurized and exhausted after detoxification. The fourth pump P4 is a vacuum pump that is driven when the main chamber 11 and the sub chamber 12 are evacuated.

The HNO ₃ conversion unit 51 converts NO ₂ contained in the sterilized gas into HNO ₃ . In order to perform this conversion, the HNO ₃ conversion unit 51 includes an ozone generator that generates ozone (O ₃ ) and a water introduction device that supplies water (H ₂ O). By adding O ₃ and H ₂ O to the NO ₂ gas passing through the HNO ₃ converter 51, the gas is chemically converted into a gas containing HNO ₃ .

The filter 52 is a filter that adsorbs HNO ₃ in the gas. As this filter 52, the same filter as the filter 331 (FIG. 6) of the circulation system 30 can be used. For example, a filter in which a nitric acid-adsorbing coating layer is applied to a substrate having a ceramic honeycomb structure is used. be able to.

  Next, an electrical control configuration of the sterilizer 1 will be described with reference to FIG. Although not shown in FIG. 3, the sterilizer 1 includes a control device 70 (control means) for electrically controlling the operation of the sterilizer 1. The control device 70 includes a CPU (central processing unit) that performs information processing and the like, and is configured to include a functional unit illustrated in FIG. 5 by executing software programmed to control the operation of the sterilization device 1. To work. The control device 70 functionally includes an overall control unit 71, a pump control unit 72, a solenoid valve control unit 73, a plasma control unit 74, a lock control unit 75, and a dryer control unit 76.

The overall control unit 71 manages the overall operation mode of the sterilization apparatus 1 and gives a control signal for notifying the individual control units 72 to 76 of the change and maintenance of the operation mode. The concentration data of NO ₂ in the main chamber 11 and the sub chamber 12 measured by the first and second concentration sensors 111 and 121, and the inside of the main chamber 11 and the sub chamber 12 measured by the first and second pressure sensors 112 and 122, respectively. The pressure data is input to the overall control unit 71. The overall control unit 71 manages the operation mode of the sterilizer 1 based on these concentration data and pressure data, time data provided from a timer device (not shown), and the like.

  The pump control unit 72 gives a control signal for controlling execution and stoppage of the pump operation to the first to fourth pumps P1 to P4 individually according to the operation mode. The electromagnetic valve control unit 73 gives a control signal for opening or closing the valve to the first to eighth electromagnetic valves V1 to V8 individually according to the operation mode.

  The plasma control unit 74 gives the microwave supply device 60 a control signal for controlling the start or stop thereof. That is, the plasma control unit 74 controls a period for generating plasma in the plasma nozzle 31.

  The lock control unit 75 controls the operation of the chamber lock device 13. The chamber lock device 13 is a device that interlocks an opening / closing door for loading and unloading the object to be processed provided in the main chamber 11 (not shown in FIG. 3). The door of the main chamber 11 is locked by a chamber lock device 13 for ensuring safety during a series of sterilization processes for an object to be processed.

  The dryer control unit 76 controls the ON-OFF operation of the air dryer 21. Humidity data measured by the humidity sensor 22 is output to the dryer control unit 76. When the humidity data is an abnormal value indicating that the air dryer 21 has failed in operation, the dryer control unit 76 outputs an abnormal signal to the overall control unit 71 to notify the user of the abnormality.

  FIG. 8 is a timing chart showing the operation of the sterilizer 1 controlled by the controller 70. FIG. 9 is a tabular diagram showing control states of the first to fourth pumps P1 to P4, and FIG. 10 is a tabular diagram showing control states of the first to eighth electromagnetic valves V1 to V8. . In FIG. 9, a circle indicates that the pump is operating and a cross indicates that the pump is stopped. In FIG. 10, a circle indicates that the solenoid valve is “open” and a cross indicates that it is “closed”. Each state is shown. Note that one “process content” column in the horizontal column of FIG. 8 is linked to the “process” column in the leftmost vertical column of FIGS. 9 and 10.

Time T1 is the time when the user presses the start button of the sterilizer 1 and a series of sterilization processing steps are started. As shown in FIG. 8, the sterilization process includes a first drying process for drying the object to be processed, a sterilization preparation process for generating NO ₂ gas as a sterilizing material, and bringing the object to be processed into contact with NO ₂ gas. A sterilization process for sterilizing the object to be processed, an exhaust gas detoxification process for purifying NO ₂ gas remaining after the sterilization process, and a second drying process for drying the object to be processed again. It is assumed that an object to be processed such as a medical instrument is accommodated in the main chamber 11 before time T1.

The first drying process includes an evacuation process for highly evacuating the main chamber 11 and the sub-chamber 12, a holding process for maintaining the state for a certain period of time, and dry air that is a raw material for generating NO ₂ gas in the sub-chamber 12. And the intake process.

  The overall control unit 71 of the control device 70 first gives an instruction to lock the open / close door of the main chamber 11 to the lock control unit 75 at time T1. In response to this, the lock controller 75 drives the chamber lock device 13 to interlock the open / close door of the main chamber 11. At the same time, in order to execute the exhaust process, the operation mode is set to “exhaust mode”, and the individual control units 72 to 76 are notified of the mode setting signal.

  When the exhaust mode is set, the pump control unit 72 operates the third and fourth pumps P3 and P4, and the electromagnetic valve control unit 73 sets the fourth, sixth, and eighth electromagnetic valves V4, V6, and V8 to “ Open. By only opening these solenoid valves, exhaust from the sub chamber 12 to the fourth pump P4 via the fourth vacuum pipe 401, the main chamber 11, the sixth vacuum pipe 501, and the fourth atmospheric pressure pipe 503 is performed. A path is formed. The main chamber 11 and the sub-chamber 12 are evacuated by driving the third and fourth pumps P3 and P4.

  The overall control unit 71 receives pressure data from the first and second pressure sensors 112 and 122 every predetermined sampling period, and monitors the pressures of the main chamber 11 and the sub chamber 12. If it is determined that the predetermined degree of vacuum (1 Torr is illustrated in FIG. 8) has been reached at time T2 based on the pressure data, the overall control unit 71 sets the operation mode to “holding mode” in order to execute the holding step. To do.

  The holding mode is a mode in which all of the first to fourth pumps P1 to P4 are stopped and all of the first to eighth electromagnetic valves V1 to V8 are “closed”. In FIG. 9 and FIG. 10, the description of the state of the holding process corresponding to this holding mode is omitted. Therefore, when the holding mode is set, the pump control unit 72 stops the third and fourth pumps P3 and P4, and the electromagnetic valve control unit 73 sets the fourth, sixth, and eighth electromagnetic valves V4, V6, and V8. Is “closed”. The overall control unit 71 causes the timer device to start timing from time T2, and maintains the holding mode until time T3 when a predetermined time elapses. By continuing this holding process for a certain period of time, the inside of the main chamber 11, the object to be processed accommodated therein, and the inside of the sub chamber 12 are dried. Further, the vacuum state in the main chamber 11 and the sub chamber 12 is stabilized.

  At time T3, the overall control unit 71 sets the operation mode to “intake mode” in order to execute the intake process. Since the intake process is intended to introduce dry air into the sub-chamber 12 under reduced pressure, the pump control unit 72 operates only the first pump P1, and the electromagnetic valve control unit 73 uses the first electromagnetic valve V1. Only “open”. The dryer control unit 76 operates the air dryer 21. In this state, the air sucked from the outside by the first pump P1 is highly dried by the air dryer 21 and passes through the first normal pressure pipe 201 and the first vacuum pipe 202 into the subchamber 12. be introduced. The drying process is continued in the main chamber 11 during this intake process (and during the next sterilization preparation process).

  During the intake mode, the overall control unit 71 receives pressure data from the second pressure sensor 122 every sampling period and monitors the pressure in the sub-chamber 12. If it is determined that the normal pressure (760 Torr) has been reached at time T4 based on the pressure data, the overall control unit 71 ends the intake mode. Further, the dryer control unit 76 stops the air dryer 21.

Subsequently, a sterilization preparation process is executed. This step comprises a plasma step of generating NO ₂ gas by ionizing air with plasma in order to fill the sub-chamber 12 with a predetermined concentration of sterilizing gas.

At time T4, the overall control unit 71 sets the operation mode to “plasma mode” for the execution of the plasma process. When the plasma mode is set, the pump control unit 72 operates only the second pump P2, and the electromagnetic valve control unit 73 opens the second and third electromagnetic valves V2 and V3. As a result, one sealed space composed of the sub-chamber 12, the second vacuum pipe 301, the second atmospheric pressure pipe 303, and the third vacuum pipe 302 is formed, and air (NO ₂ gas) circulates in the sealed space. It becomes possible.

Further, at time T4, the plasma control unit 74 operates the microwave supply device 60. Accordingly, the microwave supply device 60 supplies microwave energy to the plasma nozzle 31, and plasma is generated at the plasma nozzle 31. At this time, since the accompanying cylindrical space 312H is in a state where the pressure is reduced from the atmospheric pressure by the operation of the second pump P2, the lighting property of the plasma is good and the lighting state is maintained well. The air circulating through the plasma nozzle 31 is ionized, and further passes through the NO ₂ converter 33 to be converted into NO ₂ gas. By continuing this state, the air in the sub-chamber 12 is gradually converted into NO ₂ gas.

During the plasma mode, the overall control unit 71 receives NO ₂ concentration data from the second concentration sensor 121 every sampling period, and monitors the NO ₂ concentration in the sub-chamber 12. If it is determined that the NO ₂ concentration has reached a predetermined value (NO ₂ concentration D described later) based on the concentration data, the overall control unit 71 ends the plasma mode. Accordingly, the plasma control unit 74 stops the operation of the microwave supply device 60.

Next, a sterilization process is performed. In the sterilization process, NO ₂ gas filled in the sub-chamber 12 under normal pressure is introduced at once into the main chamber 11 containing the object to be processed and under a high vacuum using the pressure difference between the two chambers. At the same time, a sterilization process is performed in which the object to be processed is exposed to NO ₂ gas. This sterilization process is a sterilization process that satisfies the following equation when the exposure time of the object to be treated with NO ₂ gas is T (min) and the NO ₂ concentration in the main chamber 11 is D (kppm).
T × D ≧ 1000 (kppm · min) where T ≦ 120 min

  At time T5, the overall control unit 71 sets the operation mode to “circulation mode” for the execution of the sterilization process. When the circulation mode is set, the pump control unit 72 operates only the third pump P3, and the electromagnetic valve control unit 73 sets the fourth and fifth electromagnetic valves V4 and V5 to “open”. As a result, the main chamber 11 and the sub-chamber 12 become one sealed space connected by the fourth vacuum pipe 401 and the fifth vacuum pipe 402.

As a result, NO ₂ gas suddenly enters the main chamber 11 under reduced pressure, and the object to be processed in the chamber is well exposed to the NO ₂ gas. For example, even if the object to be processed is an elongated tube such as a catheter, NO ₂ gas spreads to the minute space in the tube. Therefore, good sterilization of the workpiece can be performed.

As the introduction of NO ₂ gas into the main chamber 11 progresses, the pressure difference between the main chamber 11 and the sub-chamber 12 decreases. At a certain time T51, the pressures in both chambers are balanced. After time T51, NO ₂ gas in the sub chamber 12 is sent to the main chamber 11 exclusively by the operation of the third pump P3. The overall control unit 71 causes the timer device to start measuring time from time T5 and maintains the circulation mode until time T6 when the time that satisfies the above condition T × D ≧ 1000 elapses.

By such a sterilization process, the object to be processed is in a sterilized state, but NO ₂ gas and a substance generated by the sterilization reaction remain in the main chamber 11 and the sub chamber 12. In order to purify these, an exhaust gas detoxification process is performed. This step includes a return step for returning the inside of the main chamber 11 and the sub chamber 12 to normal pressure, and a purification step for purifying residual NO ₂ gas.

  At time T6, the overall control unit 71 sets the operation mode to “return mode” for executing the return step. When the return mode is set, the pump controller 72 newly operates the first pump P1 and continues the operation of the third pump P3. The electromagnetic valve control unit 73 sets the first and fourth electromagnetic valves V1 and V4 to “open”. As a result, outside air is introduced into the main chamber 11 and the sub chamber 12 in a reduced pressure state via the first atmospheric pressure pipe 201, the first vacuum pipe 202 and the fourth vacuum pipe 401.

  During the return mode, the overall control unit 71 receives pressure data from the first and second pressure sensors 112 and 122 every sampling period and monitors the pressures of the main chamber 11 and the sub chamber 12. When it is determined based on the pressure data that both chambers have reached the normal pressure at time T7, the overall control unit 71 ends the return mode.

  At time T7, the overall control unit 71 sets the operation mode to “purification mode” in order to execute the purification process. When the purification mode is set, the pump control unit 72 activates the second and third pumps P2 and P3, and the solenoid valve control unit 73 performs the second, third, fourth, sixth, and seventh solenoid valves V2. , V3, V4, V6, and V7 are set to “open”. At this time, since the first electromagnetic valve V1 and the eighth electromagnetic valve V8 are “closed”, the sealing performance in the main chamber 11 and the sub chamber 12 is ensured.

On the other hand, one circulation path passing through the main chamber 11, the exhaust system 50, the linkage system 40, the sub-chamber 12 and the circulation system 20 is formed. Starting from the main chamber 11, the piping in the exhaust system 50, the seventh vacuum piping 502, the fifth vacuum piping 402, the sub-chamber 12, and the NO ₂ conversion portion to which the HNO ₃ conversion portion 51 and the filter 52 are attached are sequentially provided. A sealed circulation path is formed that returns to the main chamber 11 via the piping of the circulation system 20 to which the 33 is attached and the fourth vacuum piping 401.

In the present embodiment, the detoxification process is performed inside such a sealed circulation path (sealed space). That is, an air flow is generated in the circulation path by driving the second and third pumps P2 and P3. Therefore, the residual NO ₂ gas in the main chamber 11 and the sub chamber 12 passes through the HNO ₃ converter 51 and the filter 52. Thus, the residual NO ₂ gas is once converted into a gas containing HNO ₃ , and then HNO ₃ is adsorbed by the filter 52 to become a gas containing low concentrations of NO ₂ and HNO ₃ . Thereafter, the low-concentration gas enters the sub-chamber 12 and further passes through a filter 331 (FIG. 6) provided in the NO ₂ conversion unit 33 of the circulation system 20. At this time, HNO ₃ remaining in the gas is adsorbed by the filter 331. The filtered gas returns to the sub chamber 12 again, and returns to the main chamber 11 through the fourth vacuum pipe 401.

The above cycle is repeated, and the residual NO ₂ gas is gradually purified. During the purification mode, the overall control unit 71 receives NO ₂ concentration data from the first and second concentration sensors 111 and 121 for each sampling period, and monitors the NO ₂ concentrations in the main chamber 11 and the sub chamber 12. If it is determined based on the concentration data that the NO ₂ concentration has decreased below the predetermined value at time T8, the overall control unit 71 ends the purification mode.

  Finally, the second drying process is performed. This process is a process for drying the object to be processed after sterilization, exhausting the inside of the main chamber 11 and the sub-chamber 12 and removing the residue, and includes an exhaust process, a holding process, and a return process. Become. Each of these steps is the same operation step as described above.

  That is, at time T8, the overall control unit 71 sets the operation mode to “exhaust mode” for execution of the exhaust process. Along with this, the pump control unit 72 newly operates the fourth pump P4 instead of the second pump P2, and continues the operation of the third pump P3. The solenoid valve control unit 73 sets the fourth, sixth, and eighth solenoid valves V4, V6, and V8 to “open”. Thereby, the main chamber 11 and the sub chamber 12 are evacuated. At this time, clean gas after purification is discharged from the fourth pump P4. In the “exhaust mode”, the second and third electromagnetic valves V2 and V3 are “closed”, so that the plasma nozzle 31 having a relatively low resistance to vacuum can be protected.

  The overall control unit 71 receives pressure data from the first and second pressure sensors 112 and 122 every sampling period, and monitors the pressure in the main chamber 11 and the sub chamber 12. If it is determined that the predetermined degree of vacuum has been reached at time T9 based on the pressure data, the overall control unit 71 sets the operation mode to “holding mode” in order to execute the holding step. As a result, all of the first to fourth pumps P1 to P4 are stopped, and all of the first to eighth electromagnetic valves V1 to V8 are “closed”.

  The overall control unit 71 causes the timer device to start timing from time T9 and maintains the holding mode until time T10 when a predetermined time elapses. By continuing this holding process for a certain time, the object to be processed is brought into a dry state, and the inside of the main chamber 11 and the sub chamber 12 is cleaned.

  At time T10, the overall control unit 71 sets the operation mode to “return mode”. When the return mode is set, the pump control unit 72 operates the first and third pumps P1 and P3, and the solenoid valve control unit 73 opens the first, fourth, and fifth solenoid valves V1, V4, and V5. " As a result, outside air is introduced into the main chamber 11 and the sub-chamber 12 in a decompressed state.

  During the return mode, the overall control unit 71 receives pressure data from the first and second pressure sensors 112 and 122 every sampling period and monitors the pressures of the main chamber 11 and the sub chamber 12. If it is determined that both chambers have reached the normal pressure at time T11 based on the pressure data, the overall control unit 71 ends the return mode. Further, the chamber lock device 13 is driven via the lock control unit 75 to release the interlock of the open / close door of the main chamber 11. With this release, the user can take out the workpiece from the main chamber 11.

According to the sterilization apparatus 1 described above, after sterilizing an object to be processed in the main chamber 11, it is circulated between the main chamber 11 and the sub-chamber 12 which are in a sealed state to render the residual NO ₂ gas harmless. Can do. Thereafter, the main chamber 11 and the sub chamber 12 are evacuated. Therefore, the certainty of the detoxification process can be ensured.

  In addition, in the circulation system 30, due to the generation of a gas flow accompanying the operation of the second pump P <b> 2, the inside of the cylindrical space 312 </ b> H and the insulating pipe 315 becomes slightly negative pressure, and stable lighting of plasma in the plasma nozzle 31 The maintenance of the lighting state is ensured.

As mentioned above, although it demonstrated per embodiment of this invention, this invention is not limited to this, Various deformation | transformation embodiment can be taken. For example, in the above-described embodiment, an example in which NO ₂ gas is used as the nitrogen oxide gas has been shown, but various nitrogen oxide gases other than NO ₂ gas may be used as the sterilizing agent.

1 Sterilizer 11 Main chamber (first chamber)
12 Subchamber (second chamber)
20 Intake system 30 Circulation system 40 Linkage system 401 Fourth vacuum pipe (first pipe)
402 5th vacuum pipe (second pipe)
50 Exhaust system 60 Microwave supply device 70 Control device (control means)
100 Sterilizer 101 Introduction unit 102 Sterilization room (sealed space)
DESCRIPTION OF SYMBOLS 103 Plasma generation part 104 Catalyst part 105 Purification apparatus 109 Control part P1-P4 1st-4th pump (P3: Circulation means)
V1 to V8 1st to 8th solenoid valves (V4, V5: 1st valve, 2nd valve, 3rd valve)
FV flow control valve

Claims (4)

A method of performing a sterilization process in which an object to be processed is exposed to a sterilant in a sealed space,
Using nitrogen oxide gas as the sterilant,
As the sterilization treatment, when the exposure time of the object to be treated with the nitrogen oxide gas is T (min) and the concentration of the nitrogen oxide gas in the sealed space is D (kppm), the sterilization treatment satisfying the following formula: A sterilization method characterized by:
T × D ≧ 1000 (kppm · min) where T ≦ 120 min The sterilization treatment is
A first step of sealing a space for accommodating the object to be processed to form a sealed space, and gradually increasing the nitrogen oxide gas concentration in the sealed space;
A second step of holding the sealed space for a predetermined time after reaching a predetermined concentration,
2. The sterilization method according to claim 1, wherein the concentration D of the nitrogen oxide gas is an equivalent concentration obtained by combining the first step and the second step.   The sterilization method according to claim 1 or 2, wherein the nitrogen oxide gas is a gas containing nitrogen dioxide as a main component. A first chamber in which an object to be processed is accommodated;
A second chamber in which nitrogen oxide gas as a sterilant is generated;
A first pipe forming a communication path from the second chamber to the first chamber;
A second pipe forming a communication path from the first chamber to the second chamber;
A first valve and a second valve respectively disposed in the first pipe and the second pipe;
A circulation means for circulating gas in a sealed space formed by the first pipe and the second pipe, the first chamber, and the second chamber;
Control means for controlling the operation of the first valve, the second valve and the circulation means,
The control means includes
The first valve and the second valve are opened, the circulation means is driven to circulate a gas containing the nitrogen oxide gas in the sealed space, and the object to be processed is the nitrogen oxide gas. Sterilization treatment to expose to gas containing,
When the exposure time of the object to be treated with the nitrogen oxide gas is T (min) and the concentration of the nitrogen oxide gas in the sealed space is D (kppm), a sterilization process that satisfies the following formula is performed. The sterilizer is characterized by maintaining the circulation.
T × D ≧ 1000 (kppm · min) where T ≦ 120 min

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